Liquid ejection device

ABSTRACT

A liquid ejection device includes: an ejecting unit configured to eject a liquid from a nozzle in a first direction; and a light source unit configured to emit light in a first optical path and a second optical path which are arranged such that the first optical path and the second optical path intersect on an extension line in the first direction from the nozzle. With the liquid ejection device having such a configuration, it becomes easy to eject the liquid at a position having a preferable interval with respect to an object.

The present application is based on, and claims priority from JPApplication Serial Number 2020-014618, filed Jan. 31, 2020, thedisclosure of which is hereby incorporated by reference herein in itsentirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a liquid ejection device.

2. Related Art

In the related art, various liquid ejection devices that eject a liquidto an object are used. In such a liquid ejection device, it is requiredto eject the liquid at a position where a preferable interval withrespect to the object is obtained. For example, in an inkjet printer, adistance from an ink ejection nozzle to a recording medium is severelyadjusted. For example, Japanese Translation of PCT InternationalApplication Publication No. JP-T-2019-517836 discloses a visibletoothbrush capable of ejecting a liquid to an affected area as an objectwhile illuminating the affected area with illumination.

However, for example, a mechanism for adjusting a distance from theejection nozzle to the medium in the inkjet printer tends to becomplicated. Ina configuration in which the liquid is ejected to theobject while simply illuminating the object with illumination, such asthe visible toothbrush of JP-T-2019-517836, it is difficult to grasp apreferable interval from an ejecting unit to the object because a properposition with respect to the object is not indicated.

SUMMARY

A liquid ejection device according to the present disclosure includes:an ejecting unit configured to eject a liquid from a nozzle in a firstdirection; and a light source unit configured to emit light in a firstoptical path and a second optical path which are arranged such that thefirst optical path and the second optical path intersect on an extensionline in the first direction from the nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a liquid ejection device accordingto a first embodiment in a state in which an intersection position of afirst optical path and a second optical path is a droplet formationposition.

FIG. 2 is a schematic diagram showing the liquid ejection deviceaccording to the first embodiment in a state in which the intersectionposition of the first optical path and the second optical path is notthe droplet formation position.

FIG. 3 is a cross-sectional view showing an ejecting unit of the liquidejection device according to the first embodiment.

FIG. 4 is a diagram showing a state in which an interval from theejecting unit to an object matches a distance from the ejecting unit tothe intersection position of the first optical path and the secondoptical path in the liquid ejection device according to the firstembodiment.

FIG. 5 is a schematic diagram showing positions of the first opticalpath and the second optical path on the object in the state of FIG. 4.

FIG. 6 is a diagram showing a state in which the interval from theejecting unit to the object is larger than the distance from theejecting unit to the intersection position of the first optical path andthe second optical path in the liquid ejection device according to thefirst embodiment.

FIG. 7 is a schematic diagram showing the positions of the first opticalpath and the second optical path on the object in the state of FIG. 6.

FIG. 8 is a diagram showing a state in which the interval from theejecting unit to the object is smaller than the distance from theejecting unit to the intersection position of the first optical path andthe second optical path in the liquid ejection device according to thefirst embodiment.

FIG. 9 is a schematic diagram showing the positions of the first opticalpath and the second optical path on the object in the state of FIG. 8.

FIG. 10 is a schematic diagram showing a liquid ejection deviceaccording to a second embodiment.

FIG. 11 is a schematic diagram showing a liquid ejection deviceaccording to a third embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

First, the present disclosure will be briefly described.

A liquid ejection device according to a first aspect of the presentdisclosure includes: an ejecting unit configured to eject a liquid froma nozzle in a first direction; and alight source unit configured to emitlight in a first optical path and a second optical path which arearranged such that the first optical path and the second optical pathintersect on an extension line in the first direction from the nozzle.

According to the present aspect, the first optical path and the secondoptical path intersect on the extension line in the first direction,which is an ejection direction of the liquid, from the nozzle.Therefore, with a simple configuration in which the first optical pathand the second optical path intersect on the extension line from thenozzle, it is possible to easily grasp, based on an intersectionposition of the first optical path and the second optical path, aposition where a preferable interval with respect to an object isobtained, and it is possible to easily dispose the liquid ejectiondevice with a preferable interval with respect to the object.

The liquid ejection device according to a second aspect of the presentdisclosure is directed to the first aspect, in which the light sourceunit is configured to adjust an intersection position of the firstoptical path and the second optical path on the extension line.

According to the present aspect, the light source unit can adjust theintersection position of the first optical path and the second opticalpath on the extension line. Therefore, when the preferable interval withrespect to the object changes according to an ejection state of theliquid, it is possible to easily dispose the liquid ejection device witha preferable interval with respect to the object by adjusting theintersection position.

The liquid ejection device according to a third aspect of the presentdisclosure is directed to the first aspect or the second aspect, inwhich the ejecting unit has a configuration in which the liquid iscontinuously ejected from the nozzle, and the liquid in a continuousstate is formed into a droplet at a droplet formation position on theextension line.

When the liquid ejection device is used in which the ejecting unit has aconfiguration in which the liquid is continuously ejected from thenozzle and the liquid in the continuous state is formed into the dropletat the droplet formation position on the extension line, the liquidejection device is preferably disposed such that the object is disposedat a position where the liquid is formed into the droplet so as toobtain a preferable interval with respect to the object. According tothe present aspect, in the liquid ejection device having such aconfiguration, the liquid ejection device can be easily disposed at apreferable position.

The liquid ejection device according to a fourth aspect of the presentdisclosure is directed to the third aspect, in which an intersectionposition of the first optical path and the second optical path on theextension line is the droplet formation position.

According to the present aspect, in the light source unit, theintersection position of the first optical path and the second opticalpath on the extension line is the droplet formation position. Therefore,the liquid ejection device can be easily disposed at a preferableposition.

The liquid ejection device according to a fifth aspect of the presentdisclosure is directed to the fourth aspect, in which the liquidejection device further includes: a processor configured to control anejection state of the liquid ejected by the ejecting unit and adjust theintersection position by the light source unit, and the processoradjusts the intersection position according to the ejection state.

According to the present aspect, the processor adjusts the intersectionposition of the first optical path and the second optical path on theextension line according to the ejection state of the liquid ejected bythe ejecting unit. Therefore, even when the ejection state of the liquidejected by the ejecting unit is changed, the intersection position canbe adjusted under automatic control of the processor, so that the liquidejection device can be easily disposed at a preferable position.

The liquid ejection device according to a sixth aspect of the presentdisclosure is directed to the fifth aspect, in which the liquid ejectiondevice further includes: a pump configured to change a flow rate of theliquid in the nozzle, a flowmeter configured to measure the flow rate,and a memory configured to store data related to the intersectionposition based on the flow rate, and the processor adjusts theintersection position based on a flow rate measurement result of theflowmeter and the data stored in the memory.

According to the present aspect, the flow rate of the liquid can beeasily changed by the pump. In addition, even when the ejection state ofthe liquid ejected by the ejecting unit is changed by changing the flowrate of the liquid, the intersection position can be adjusted under theautomatic control of the processor, so that the liquid ejection devicecan be easily disposed at a preferable position.

The liquid ejection device according to a seventh aspect of the presentdisclosure is directed to one of the first to sixth aspects, in whichthe light in the first optical path and the light in the second opticalpath is both visible light and has different wavelengths.

If the wavelengths of the light in the first optical path and the lightin the second optical path are the same, when the intersection positionof the first optical path and the second optical path on the extensionline is deviated, it may be difficult to determine whether the intervalwith respect to the object is deviated to a near side or a far side.However, according to the present aspect, since the light in the firstoptical path and the light in the second optical path is visible lighthaving different wavelengths, a positional relationship between thelight in the first optical path and the light in the second optical pathis reversed depending on whether the interval with respect to the objectis deviated to the near side or the far side. Therefore, the liquidejection device can be easily disposed at a preferable position.

Hereinafter, embodiments of the present disclosure will be describedwith reference to accompanying drawings.

First Embodiment

First, a liquid ejection device 1A according to a first embodiment as aliquid ejection device 1 according to the present disclosure will bedescribed with reference to FIGS. 1 to 9. As will be described in detaillater, an ejecting unit 2 of the liquid ejection device 1A according tothe present embodiment has a configuration in which a liquid 4 can becontinuously ejected from a nozzle 22 and a liquid 4 a in a continuousstate can be formed into a droplet 4 b at a droplet formation position 4c on an extension line in an ejection direction D of the liquid 4.However, the present disclosure is not limited to the liquid ejectiondevice including such an ejecting unit. For example, a configuration maybe adopted in which the ejecting unit such as that used in a generalinkjet printer is provided.

The liquid ejection device 1A shown in FIGS. 1 and 2 includes theejecting unit 2, a light source unit 3, a liquid container 8 for storingthe liquid 4, a liquid supply pipe 7 coupling the ejecting unit 2 andthe liquid container 8, a pump 6, and a control unit 5. Such a liquidejection device 1A performs various kinds of work by disposing theejecting unit 2 with a desired interval with respect to an object 0using the light source unit 3, ejecting the liquid 4 from the ejectingunit 2, and the liquid 4 colliding with the object O as shown in FIG. 4or the like. Examples of the various kinds of work include cleaning,deburring, peeling, trimming, excising, incising, and crushing.Hereinafter, each unit of the liquid ejection device 1A will bedescribed in detail.

Ejecting Unit

As shown in FIG. 3, the ejecting unit 2 includes the nozzle 22, a liquidtransporting pipe 24, and a pulsation generation unit 26. Among thesecomponents, the nozzle 22 ejects the liquid 4 toward the object O. Theliquid transporting pipe 24 is a flow path that couples the nozzle 22and the pulsation generation unit 26. The liquid transporting pipe 24transports the liquid 4 from the pulsation generation unit 26 to thenozzle 22. Further, the pulsation generation unit 26 applies a flow ratepulsation to the liquid 4 supplied from the liquid container 8 throughthe liquid supply pipe 7. By applying a pulsation to the liquid 4 thus,a flow velocity of the liquid 4 ejected from the nozzle 22 periodicallyfluctuates. Accordingly, a distance until the liquid 4 a in a continuousstate ejected from the nozzle 22 is changed into the droplet 4 b, thatis, a droplet formation distance can be shortened. That is, the ejectingunit 2 according to the present embodiment is configured to change adistance of the droplet formation position 4 c to the nozzle 22. Theliquid 4 b formed into the droplet eventually becomes a diffusion jetthat deviates significantly from the extension line in the ejectiondirection D. In this case, since the number of the droplets 4 b on theextension line in the ejection direction D is reduced, a desired effectcannot be obtained. That is, the droplet formation position 4 cindicating a position where the continuous liquid 4 a is changed intothe droplet 4 b to a position where the diffusion jet is formed is aposition at which an energy applied to the outside by the liquid 4ejected from the nozzle 22 is the largest. A boundary between thedroplet formation position 4 c and a diffusion jet region can bedetermined by the fact that an energy application to the object Ochanges significantly when a position of the object O on the extensionline in the ejection direction D is changed due to flight of the droplet4 b significantly deviating from the extension line in the ejectiondirection D, for example. Even if the energy applied to the object O isnot measured, the boundary can also be determined by observing theflight of the droplet 4 b, such as setting a threshold value showing howmuch the flight of the droplet 4 b deviates from the extension line inthe ejection direction D, and recombining the droplet 4 b.

Hereinafter, each component of the ejecting unit 2 will be described indetail. The nozzle 22 is attached to a tip end portion of the liquidtransporting pipe 24. The nozzle 22 is internally provided with a nozzleflow path 220 through which the liquid 4 passes. An inner diameter of atip end portion of the nozzle flow path 220 is smaller than an innerdiameter of a base end portion of the nozzle flow path 220. The liquid 4transported towards the nozzle 22 in the liquid transporting pipe 24 isformed into a trickle through the nozzle flow path 220 and is ejected.The nozzle 22 may be a member provided separately from the liquidtransporting pipe 24 or may be integral with the liquid transportingpipe 24.

The liquid transporting pipe 24 is a pipe that couples the nozzle 22 andthe pulsation generation unit 26, and a liquid flow path 240 fortransporting the liquid 4 is provided inside the liquid transportingpipe 24. The nozzle flow path 220 communicates with the liquid supplypipe 7 via the liquid flow path 240. The liquid supply pipe 7 may be astraight pipe, or may be a curved pipe in which a part of or the entirepipe is curved.

The nozzle 22 and the liquid transporting pipe 24 may have rigidity suchthat the nozzle 22 and the liquid transporting pipe 24 do not deformwhen the liquid 4 is ejected. Examples of a constituent material of thenozzle 22 include such as a metal material, a ceramic material, and aresin material. Examples of a constituent material of the liquidtransporting pipe 24 include such as a metal material and a resinmaterial, and the metal material is particularly preferably used.

The inner diameter of the nozzle flow path 220 is appropriately selectedaccording to a work content, a material of the object O, and the like,and is preferably, for example, 0.01 mm or more and 1.00 mm or less, andmore preferably 0.02 mm or more and 0.30 mm or less.

The pulsation generation unit 26 includes a housing 261, a piezoelectricelement 262 and a reinforcing plate 263 that are provided in the housing261, and a diaphragm 264. The housing 261 has a box shape, and includesa first case 261 a, a second case 261 b, and a third case 261 c. Each ofthe first case 261 a and the second case 261 b has a cylindrical shapeincluding a through hole penetrating from a base end to a tip end.Further, the diaphragm 264 is interposed between an opening on a baseend side of the first case 261 a and an opening on a tip end side of thesecond case 261 b. The diaphragm 264 is, for example, a film memberhaving elasticity or flexibility.

The third case 261 c has a plate shape. The third case 261 c is fixed toan opening on a base end side of the second case 261 b. A space formedby the second case 261 b, the third case 261 c, and the diaphragm 264 isan accommodation chamber 265. The piezoelectric element 262 and thereinforcing plate 263 are accommodated in the accommodation chamber 265.A base end of the piezoelectric element 262 is coupled to the third case261 c, and a tip end of the piezoelectric element 262 is coupled to thediaphragm 264 via the reinforcing plate 263.

The through hole in the first case 261 a penetrates from the base end tothe tip end. Such a through hole includes a base end-side region havinga relatively large inner diameter and a tip end-side region having arelatively small inner diameter. In the regions, the liquid transportingpipe 24 is inserted into the region having the small inner diameter froman opening on the tip end side. In the region having the large innerdiameter, the diaphragm 264 is covered from the base end side. A spaceformed by the region having the large inner diameter and the diaphragm264 is a liquid chamber 266.

Further, a space between the liquid chamber 266 and the liquidtransporting pipe 24 is an outlet flow path 267. On the other hand, aninlet flow path 268 different from the outlet flow path 267 communicateswith the liquid chamber 266. One end of the inlet flow path 268communicates with the liquid chamber 266, and the other end is insertedwith the liquid supply pipe 7. Accordingly, an internal flow path of theliquid supply pipe 7 communicates with the inlet flow path 268, theliquid chamber 266, the outlet flow path 267, the liquid flow path 240,and the nozzle flow path 220. As a result, the liquid 4 supplied to theinlet flow path 268 via the liquid supply pipe 7 is ejected sequentiallythrough the liquid chamber 266, the outlet flow path 267, the liquidflow path 240, and the nozzle flow path 220.

A wiring 291 is drawn out from the piezoelectric element 262 via thehousing 261. The piezoelectric element 262 is electrically coupled tothe control unit 5 via the wiring 291. The piezoelectric element 262 isdriven by a drive signal S supplied from the control unit 5 and vibratesso as to repeatedly expand and contract along an X-axis, as indicated byan arrow B1 in FIG. 3, based on a reverse piezoelectric effect. When thepiezoelectric element 262 expands, the diaphragm 264 is pushed toward afirst case 261 a side. Therefore, a volume of the liquid chamber 266reduces, and the liquid 4 in the liquid chamber 266 is accelerated inthe outlet flow path 267. On the other hand, when the piezoelectricelement 262 contracts, the diaphragm 264 is drawn toward a third case261 c side. Therefore, the volume of the liquid chamber 266 expands, andthe liquid 4 in the inlet flow path 268 is decelerated or flowsbackward.

The piezoelectric element 262 may be an element that performs expandingand contracting vibration, or may be an element that performs bendingvibration. The piezoelectric element 262 includes, for example, apiezoelectric body and an electrode provided on the piezoelectric body.Examples of a constituent material of the piezoelectric body includepiezoelectric ceramics such as lead zirconate titanate (PZT), bariumtitanate, lead titanate, potassium niobate, lithium niobate, lithiumtantalate, sodium tungstate, zinc oxide, barium strontium titanate(BST), strontium bismuth tantalate (SBT), lead metaniobate, and leadscandium niobate.

The piezoelectric element 262 can be replaced with any element ormechanical element that can displace the diaphragm 264. Examples of suchan element or a mechanical element include a magnetostrictive element,an electromagnetic actuator, and a combination of a motor and a cam. Thehousing 261 may have rigidity such that the housing 261 does not deformwhen a pressure in the liquid chamber 266 is increased or decreased.

The pulsation generation unit 26 shown in FIG. 3 is provided at a baseend portion of the liquid transporting pipe 24, but a position of thepulsation generation unit 26 is not particularly limited. For example,the pulsation generation unit 26 may be provided in the middle of theliquid transporting pipe 24.

Light Source Unit

The liquid ejection device 1A according to the present embodimentincludes, as the light source unit 3, a light source unit 3A including afirst light irradiation unit 31 and a second light irradiation unit 32.The light source unit 3A has a configuration in which both the firstlight irradiation unit 31 and the second light irradiation unit 32 arefixed to an arm unit 38 at a predetermined angle, and are movable in amovement direction M that is a direction along the ejection direction Dof the liquid 4 with respect to the ejecting unit 2, as can be seen fromthe comparison between FIGS. 1 and 2.

As shown in FIGS. 1 and 2, the light source unit 3A is provided with thefirst light irradiation unit 31 and the second light irradiation unit 32such that a first optical path L1 of light emitted from the first lightirradiation unit 31 and a second optical path L2 of light emitted fromthe second light irradiation unit 32 intersect each other on theextension line in the ejection direction D from the nozzle 22. Since themovement direction M is a direction along the ejection direction D, evenwhen the light source unit 3A is moved in the movement direction M withrespect to the ejecting unit 2, the first optical path L1 and the secondoptical path L2 always intersect on the extension line in the ejectiondirection D from the nozzle 22.

By moving the light source unit 3A with respect to the ejecting unit 2in the movement direction M to adjust a position of the light sourceunit 3A, as shown in FIG. 1, an intersection position Lc of the firstoptical path L1 and the second optical path L2 can be adjusted so as tooverlap the droplet formation position 4 c. The light source unit 3Aaccording to the present embodiment is configured to be automaticallymoveable with respect to the ejecting unit 2 under the control of thecontrol unit 5, but a user can manually move the light source unit 3Awith respect to the ejecting unit 2. As shown in FIGS. 1 and 2, a scale2 a is formed on the ejecting unit 2 according to the presentembodiment, and the user can align the light source unit 3A with respectto the ejecting unit 2 with reference to the scale 2 a.

Liquid Container

The liquid container 8 stores the liquid 4. The liquid 4 stored in theliquid container 8 is supplied to the ejecting unit 2 via the liquidsupply pipe 7. As the liquid 4, for example, water is preferably used,but an organic solvent may be used. Any solute may be dissolved in thewater or the organic solvent, and any dispersoid may be dispersed in thewater or the organic solvent. The liquid container 8 may be a sealedcontainer or an open container.

Pump

The pump 6 is provided in the middle or an end portion of the liquidsupply pipe 7. The liquid 4 stored in the liquid container 8 issuctioned by the pump 6 and supplied to the ejecting unit 2 at apredetermined pressure. The control unit 5 is electrically coupled tothe pump 6 via a wiring 292. The pump 6 has a function of changing,based on a drive signal output from the control unit 5, a flow rate ofthe liquid 4 to be supplied. A flow rate in the pump 6 is preferably 1mL/min or more and 100 mL/min or less, more preferably 2 mL/min or moreand 50 mL/min or less, for example. The pump 6 is provided with ameasurement unit 6 a such as a flowmeter that measures an actual flowrate.

Control Unit

The control unit 5 is electrically coupled to the ejecting unit 2 viathe wiring 291. The control unit 5 is electrically coupled to the pump 6via the wiring 292. Further, the control unit 5 is electrically coupledto the light source unit 3 via a wiring 293. The control unit 5 shown inFIGS. 1 and 2 includes a piezoelectric element control unit 51, a pumpcontrol unit 52, a light source unit drive control unit 53, and astorage unit 54.

The piezoelectric element control unit 51 outputs the drive signal S tothe piezoelectric element 262. Driving of the piezoelectric element 262is controlled by the drive signal S. Accordingly, the diaphragm 264 canbe displaced, for example, at a predetermined frequency and by apredetermined displacement amount. The pump control unit 52 outputs adrive signal to the pump 6. Driving of the pump 6 is controlled by thedrive signal. Accordingly, the liquid 4 can be supplied to the ejectingunit 2, for example, at a predetermined pressure and for a predetermineddrive time. The light source unit drive control unit 53 controls themovement of the first light irradiation unit 31 and the second lightirradiation unit 32 in the movement direction M. The control unit 5 cancontrol the driving of the pump 6 and the driving of the piezoelectricelement 262 in cooperation with each other.

The control unit 5 reads optimum distance data stored in the storageunit 54 based on a set flow rate that is set by the user using a controlpanel (not shown) or the like or a measurement flow rate as ameasurement result of the measurement unit 6 a provided in the pump 6.The distance data is data of the distance from the droplet formationposition 4 c to the nozzle 22, and corresponds to data of an optimumdistance from the nozzle 22 to the object O. A table of the optimumdistance data corresponding to the set flow rate and the measurementflow rate is stored in the storage unit 54, and the light source unitdrive control unit 53 moves the light source unit 3 to a desiredposition with respect to the ejecting unit 2 based on the table.Specifically, for example, a position of the light source unit 3 withrespect to the ejecting unit 2 is changed from a state shown in FIG. 2to a state shown in FIG. 1. In the present embodiment, a tableassociating the set flow rate and the measurement flow rate with thedistance data is stored in the storage unit 54, but a relationalexpression associating the set flow rate and the measurement flow ratewith the distance data may be stored instead of such a table.

Such a function of the control unit 5 is realized by hardware such as aprocessor, a memory, and an external interface. Examples of thearithmetic unit include such as a central processing unit (CPU), adigital signal processor (DSP), and an application specific integratedcircuit (ASIC). Examples of the memory include such as a read onlymemory (ROM), a flash ROM, a random access memory (RAM), and a harddisk.

Position of Liquid Ejection Device with Respect to Object

Next, how to align a position of the liquid ejection device 1A withrespect to the object O will be described using the liquid ejectiondevice 1A according to the present embodiment.

First, after the position of the light source unit 3 with respect to theejecting unit 2 is adjusted to a desired position under the control ofthe control unit 5, the user sets the liquid ejection device 1A at atemporary position with respect to the object O. Here, the desiredposition is a position where the intersection position Lc of the firstoptical path L1 and the second optical path L2 is exactly at the dropletformation position 4 c, as shown in FIG. 1. Then, the first lightirradiation unit 31 and the second light irradiation unit 32 irradiatethe object O with light.

FIGS. 4 and 5 show a case where the intersection position Lc of thefirst optical path L1 and the second optical path L2 is exactly at awork target portion of the object O. As described above, theintersection position Lc of the first optical path L1 and the secondoptical path L2 is adjusted to be exactly at the droplet formationposition 4 c, so that in the state shown in FIGS. 4 and 5, the worktarget portion of the object O is positioned at the droplet formationposition 4 c where the highest work efficiency is obtained. Therefore,when the temporary set position of the liquid ejection device 1A is inthe states shown in FIGS. 4 and 5, the user can perform highly efficientwork by performing the work as it is.

FIGS. 6 and 7 show a case where the intersection position Lc of thefirst optical path L1 and the second optical path L2 is on a front sideof the work target portion of the object O. As described above, theintersection position Lc of the first optical path L1 and the secondoptical path L2 is adjusted to be exactly at the droplet formationposition 4 c, so that in the state shown in FIGS. 6 and 7, the worktarget portion of the object O is positioned on a far side with respectto the droplet formation position 4 c where the highest work efficiencyis obtained. Therefore, when the temporary set position of the liquidejection device 1A is in the state shown in FIGS. 6 and 7, the user canperform highly efficient work by bringing the liquid ejection device 1Acloser to the object O and by changing the set position of the liquidejection device 1A so as to be in the state shown in FIGS. 4 and 5.

FIGS. 8 and 9 show a case where the intersection position Lc of thefirst optical path L1 and the second optical path L2 is on a back sideof the work target portion of the object O. As described above, theintersection position Lc of the first optical path L1 and the secondoptical path L2 is adjusted to be exactly at the droplet formationposition 4 c, so that in the state shown in FIGS. 8 and 9, the worktarget portion of the object O is positioned on a near side with respectto the droplet formation position 4 c where the highest work efficiencyis obtained. Therefore, when the temporary set position of the liquidejection device 1A is in the state shown in FIGS. 8 and 9, the user canperform highly efficient work by bringing the liquid ejection device 1Afar from the object O and by changing the set position of the liquidejection device 1A so as to be in the state shown in FIGS. 4 and 5.

As described above, the liquid ejection device 1A of the presentembodiment includes the ejecting unit 2 that ejects the liquid 4 fromthe nozzle 22 in the ejection direction D serving as the firstdirection; and the light source unit 3 that emits light in the firstoptical path L1 and the second optical path L2 which are arranged suchthat the first optical path L1 and the second optical path L2 intersecton the extension line in the ejection direction D from the nozzle 22.The liquid ejection device 1A according to the present embodiment hassuch a configuration, so that with a simple configuration in which thefirst optical path L1 and the second optical path L2 intersect on theextension line from the nozzle 22, it is possible to easily grasp, basedon the intersection position Lc of the first optical path L1 and thesecond optical path L2, a position where a preferable interval withrespect to the object O is obtained, and it is possible to easilydispose the liquid ejection device 1A with a preferable interval withrespect to the object O.

As described above, the light source unit 3A according to the presentembodiment can adjust the intersection position Lc of the first opticalpath L1 and the second optical path L2. Therefore, in the liquidejection device 1A according to the present embodiment, when thepreferable interval with respect to the object O changes according to anejection state of the liquid 4, it is possible to easily dispose theliquid ejection device 1A with a preferable interval with respect to theobject O by adjusting the intersection position Lc.

As described above, the ejecting unit 2 according to the presentembodiment has a configuration in which the liquid 4 is continuouslyejected from the nozzle 22 and the liquid 4 a in a continuous state isformed into the droplet 4 b at the droplet formation position 4 c on theextension line in the ejection direction D from the nozzle 22. When theliquid ejection device is used in which the ejecting unit 2 has aconfiguration in which the liquid 4 is continuously ejected from thenozzle 22 and the liquid 4 a in the continuous state is formed into thedroplet at the droplet formation position 4 c on the extension line inthe ejection direction D from the nozzle 22, it is preferable to disposethe liquid ejection device, such that the object O is disposed at aposition where the liquid 4 is formed into the droplet, so as to have apreferable interval with respect to the object O. It is possible toeasily dispose the liquid ejection device 1A according to the presentembodiment at a preferable position with respect to the object O.

As described above, in the light source unit 3A according to the presentembodiment, the intersection position Lc of the first optical path L1and the second optical path L2 is automatically adjusted to the dropletformation position 4 c, so that when the liquid 4 is ejected to theobject O, the intersection position Lc is in the state of being in thedroplet formation position 4 c. Therefore, it is possible to easilydispose the liquid ejection device 1A according to the presentembodiment at a preferable position with respect to the object O.

The liquid ejection device 1A according to the present embodimentincludes the light source unit 3A capable of adjusting the intersectionposition Lc because an ejection flow rate of the liquid from theejecting unit 2 can be changed and the distance from the nozzle 22 tothe droplet formation position 4 c can be changed. However, if theejection flow rate of the liquid from the ejecting unit 2 is constantand the distance from the nozzle 22 to the droplet formation position 4c is constant, it is not necessary to adjust the intersection positionLc by aligning the position of the intersection position Lc with aposition of the droplet formation position 4 c in advance. Therefore,the liquid ejection device 1 having a configuration in which thedistance from the nozzle 22 to the droplet formation position 4 c isconstant may include the light source unit 3 that cannot adjust theintersection position Lc.

As described above, the liquid ejection device 1A according to thepresent embodiment includes the control unit 5 that controls theejection state of the liquid 4 ejected by the ejecting unit 2 and adjustthe intersection position Lc of the first optical path L1 and the secondoptical path L2 by the light source unit 3, and the control unit 5adjusts the intersection position Lc according to the ejection state ofthe liquid 4 ejected by the ejecting unit 2. Therefore, in the liquidejection device 1A according to the present embodiment, when theejection state of the liquid 4 ejected by the ejecting unit 2 ischanged, for example, from a small flow rate to a large flow rate, theintersection position Lc can be adjusted under automatic control of thecontrol unit 5, so that it is possible to easily dispose the liquidejection device 1A at a preferable position with respect to the objectO.

As described above, the liquid ejection device 1A according to thepresent embodiment includes the pump 6 that changes the flow rate of theliquid 4 in the nozzle 22. The pump 6 is provided with the measurementunit 6 a that measures the flow rate of the liquid 4. Further, a tableas data related to the intersection position Lc based on the measurementflow rate measured by the measurement unit 6 a is stored in the storageunit 54. The control unit 5 can adjust the intersection position Lcbased on the table. Thus, the liquid ejection device 1A according to thepresent embodiment can easily change the flow rate of the liquid 4 byincluding the pump 6. Further, in the liquid ejection device 1Aaccording to the present embodiment, even when the ejection state of theliquid 4 ejected by the ejecting unit 2 is changed by changing the flowrate of the liquid 4, the intersection position Lc can be adjusted underthe automatic control of the control unit 5, so that it is possible toeasily dispose the liquid ejection device 1A at a preferable positionwith respect to the object O.

Here, in the liquid ejection device 1A according to the presentembodiment, the light in the first optical path L1 is green visiblelight, and the light in the second optical path L2 is red visible light.Then, a color of the light at the intersection position Lc is yellowwhen the light in the first optical path L1 and the light in the secondoptical path L2 are combined. Thus, it is preferable that the light inthe first optical path L1 and the light in the second optical path L2 isboth visible light and is light having different wavelengths. If thewavelengths of the light in the first optical path L1 and the light inthe second optical path L2 are the same, when the intersection positionLc is deviated, it may be difficult to determine whether the intervalwith respect to the object O is deviated to the near side or the farside. However, if the light in the first optical path L1 and the lightin the second optical path L2 is visible light having differentwavelengths, as is clear from the comparison between FIGS. 7 and 9, apositional relationship between the light in the first optical path L1and the light in the second optical path L2 is reversed depending onwhether the interval of the liquid ejection device with respect to theobject O is deviated to the near side or the far side. Therefore, whenthe light in the first optical path L1 and the light in the secondoptical path L2 is both visible light and has different wavelengths, theliquid ejection device can be easily disposed at a preferable position.

Second Embodiment

Next, a liquid ejection device 1B according to a second embodiment asthe liquid ejection device 1 according to the present disclosure will bedescribed with reference to FIG. 10. FIG. 10 is a diagram correspondingto FIGS. 1 and 2 showing the liquid ejection device 1 according to thefirst embodiment, and components common to those of the first embodimentare denoted by the same reference signs in FIG. 10, and a detaileddescription thereof is omitted. Here, the liquid ejection device 1Baccording to the present embodiment has characteristics similar to thoseof the liquid ejection device 1A according to the first embodimentdescribed above, and has the same configuration as that of the liquidejection device 1A according to the first embodiment except the pointsdescribed below. Specifically, a configuration of the liquid ejectiondevice 1B is the same as that of the liquid ejection device 1A accordingto the first embodiment except a configuration of the light source unit3.

As shown in FIGS. 1 and 2, the light source unit 3A in the liquidejection device 1A according to the first embodiment has a configurationin which the intersection position Lc with respect to the dropletformation position 4 c can be changed by moving the entire light sourceunit 3A with respect to the ejecting unit 2 in the movement direction Malong the ejection direction D. On the other hand, as shown in FIG. 10,a light source unit 3B in the liquid ejection device 1B according to thepresent embodiment includes a first light irradiation unit 33 capable ofswinging in a swing direction R1 and a second light irradiation unit 34capable of swinging in a swing direction R2, and changes an angle atwhich the first light irradiation unit 33 and the second lightirradiation unit 34 are disposed under the control of the control unit5, so as to change the intersection position Lc with respect to thedroplet formation position 4 c.

Third Embodiment

Next, a liquid ejection device 1C according to a third embodiment as theliquid ejection device 1 according to the present disclosure will bedescribed with reference to FIG. 11. FIG. 11 is a diagram correspondingto FIGS. 1 and 2 showing the liquid ejection device 1 according to thefirst embodiment, and components common to those of the first embodimentand the second embodiment are denoted by the same reference signs inFIG. 11, and a detailed description thereof is omitted. Here, the liquidejection device 1C according to the present embodiment hascharacteristics similar to those of the liquid ejection device 1Aaccording to the first embodiment and the liquid ejection device 1Baccording to the second embodiment described above, and has the sameconfiguration as that of the liquid ejection device 1A according to thefirst embodiment and that of the liquid ejection device 1B according tothe second embodiment except the points described below. Specifically, aconfiguration of the liquid ejection device 1C is the same as that ofthe liquid ejection device 1A according to the first embodiment and thatof the liquid ejection device 1B according to the second embodimentexcept the configuration of the light source unit 3.

As described above, the light source unit 3A in the liquid ejectiondevice 1A according to the first embodiment and the light source unit 3Bin the liquid ejection device 1B according to the second embodimentinclude two light irradiation units. On the other hand, as shown in FIG.11, a light source unit 3C in the liquid ejection device 1C according tothe present embodiment includes one light irradiation unit 35, a lightsplitter 36 that makes incident light emit in two directions, and amirror 37 that reflects light in one direction of the light separated bythe light splitter 36. Further, the intersection position Lc withrespect to the droplet formation position 4 c can be changed bychanging, under the control of the control unit 5, an angle at which thelight irradiation unit 35, the light splitter 36, and the mirror 37 arearranged.

The present disclosure is not limited to the embodiments describedabove, and can be implemented in various configurations withoutdeparting from the scope of the disclosure. In order to solve some orall of problems described above, or to achieve some or all of effectsdescribed above, technical characteristics in the embodimentscorresponding to the technical characteristics in each embodimentdescribed in the summary of the disclosure can be replaced or combinedas appropriate. The technical characteristics can be deleted asappropriate unless the technical characteristics are described asessential in the present description.

What is claimed is:
 1. A liquid ejection device comprising: an ejectingunit configured to eject a liquid from a nozzle in a first direction;and a light source unit configured to emit light in a first optical pathand a second optical path which are arranged such that the first opticalpath and the second optical path intersect on an extension line in thefirst direction from the nozzle.
 2. The liquid ejection device accordingto claim 1, wherein the light source unit is configured to adjust anintersection position of the first optical path and the second opticalpath on the extension line.
 3. The liquid ejection device according toclaim 1, wherein the ejecting unit has a configuration in which theliquid is continuously ejected from the nozzle, and the liquid in acontinuous state is formed into a droplet at a droplet formationposition on the extension line.
 4. The liquid ejection device accordingto claim 3, wherein an intersection position of the first optical pathand the second optical path on the extension line is the dropletformation position.
 5. The liquid ejection device according to claim 4,further comprising: a processor configured to control an ejection stateof the liquid ejected by the ejecting unit and adjust the intersectionposition by the light source unit, wherein the processor adjusts theintersection position according to the ejection state.
 6. The liquidejection device according to claim 5, further comprising: a pumpconfigured to change a flow rate of the liquid in the nozzle; aflowmeter configured to measure the flow rate; and a memory configuredto store data related to the intersection position based on the flowrate, wherein the processor adjusts the intersection position based on aflow rate measurement result of the flowmeter and the data stored in thememory.
 7. The liquid ejection device according to claim 1, wherein thelight in the first optical path and the light in the second optical pathis both visible light and has different wavelengths.
 8. The liquidejection device according to claim 2, wherein the light in the firstoptical path and the light in the second optical path is both visiblelight and has different wavelengths.
 9. The liquid ejection deviceaccording to claim 3, wherein the light in the first optical path andthe light in the second optical path is both visible light and hasdifferent wavelengths.
 10. The liquid ejection device according to claim4, wherein the light in the first optical path and the light in thesecond optical path is both visible light and has different wavelengths.11. The liquid ejection device according to claim 5, wherein the lightin the first optical path and the light in the second optical path isboth visible light and has different wavelengths.
 12. The liquidejection device according to claim 6, wherein the light in the firstoptical path and the light in the second optical path is both visiblelight and has different wavelengths.